Water-Soluble Nanocrystal-Micelles: New Building Blocks for Facile Constructions of 2, 3-Dimensional Arrays |
| Dr. Hongyou Fan |
| Chemical Synthesis and Nanomaterials Department Sandia National Laboratories, Albuquerque, New Mexico
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| Wednesday, April 13th, 4:00PM |
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Nanocrystals (NCs) exhibit
unique size-dependent optical, electronic and chemical properties. The
ability to adjust properties through control of size, shape,
composition, crystallinity, and structure has led to a wide range of
potential applications for NCs in areas like optics, electronics,
catalysis, magnetic storage, and biological labeling. Furthermore, NC
assembly into 2- and 3-dimensional superlattices is of interest for
development of ‘artificial solids’ with collective optical and
electronic properties that can be further tuned by the NC spacing and
arrangement. Despite recent advances in the synthesis and
characterization of nanocrystals and nanocrystalline arrays, there
remain numerous challenges that limit their practical utilization. For
example, synthesis procedures generally used for metallic,
semiconducting, and magnetic NCs employ organic stabilizing ligands,
making the nanocrystals water insoluble. This is very problematic for
biological imaging and for incorporation of nanocrystals in hydrophilic
sol-gel matrices like silica or titania needed for the fabrication of
robust, functional lasers. In this presentation, I will report our recent results and progress on the synthesis of water-soluble NC-micelles and usage of such materials as building blocks to fabricate ordered, three-dimensional, NC/metal oxide arrays. The approach of synthesizing NC-micelles is to encapsulate organic monolayer derivatized, hydrophobic NCs within the hydrophobic interior of surfactant/lipid micelles that afford water-solubility. This approach is simple, general, can be extended to synthesize water-soluble semiconductor and magnetic NCs with different shapes. Subsequent self-assembly with metal oxides leads to highly ordered NC/metal oxides arrays with face-centered cubic mesophase. Through different reaction conditions, material forms (film, powder, particle), ordering, and orientation can be controlled. Integration of NC/metal oxide arrays will be also discussed. The method opens a new pathway to the fabrication of 2, 3-D NC superlattice inside inorganic framework with tunable dielectric. |
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